Optical bleaching compositions containing tertiary amino substituted 2-aryl aryleneazoles



United States Patent OPTICAL BLEACHING COIVIPOSITIONS CONTAIN- ING TERTIARY ANIINO SUBSTITUTED 2-ARYL ARYLENEAZOLES Julian- Jacob Leavitt, Plainfield, N. 1., assignor to American Cyanamid Company, New York, N. Y., a corporation of Maine N Drawing. Application October 14, 1953, Serial No. 386,132

Claims. (Cl.v 252-301.2)

This invention relates to new optical bleaching agents and to compositions containing them and to fibers dyed therewith. More specifically, it relates to 2-aryl aryleneazoles substituted by a tertiary amino group, and to the use of this class of compounds for the whitening of various type of fibers as defined below.

The compounds of this invention may be illustrated by the following formula:

where X may be S, NH or O and R1 and R2 are aliphatic hydrocarbon radicals. R1 and R2 may be identical or different, and they may be joined to form an alicyclic ring. These azolesmay be used alone or in mixtures with other optical bleaching agents or in mixtures with each other to obtain the most desirable hue of fluorescence.

Optical bleaching agents have appeared in great numbers on the market in the last few years. The principle of their operation is that a white dye is applied to the cloth, the said dye having a blue fluorescence which is used to cancel out optically the natural yellow of the cloth. A pure blue fluorescence cannot always be achieved readily. Some optical bleaching agents are reddish blue in hue and others have a greenish tinge. Soap'manufacturers are not agreed among themselves as to which shade of fluorescence is most desirable. Some want a redder fluorescence and some a greener fluorescence than others. The ideal situation is a pure blue fluorescence sometimes called neutral blue fluorescence.

I have found that the tertiary amino aryl aryleneazoles of this invention are particularly useful for whitening of various materials because they possess complementary hues-of fluorescence. Thus, I have found that when the tertiary amino nitrogen was bonded to the aryl ring, the compound fluoresces a reddish shade of blue. When the tertiary amino nitrogen was bonded tothe aryl'eneazole ring, the compound-fluoresces a greenish shade of blue. This permits the use of either derivatives where the exact shade is not critical or their use in combination with each other, or withcertain other types of whiteners, where a specific hue is required.

It is a particular advantage of certain blends of two different tertiary amino substituted aryl aryleneazoles which give a blue shade of fluorescence, that both products. exhaust on fiber atthe same rate and have equal fastness.

It is another advantage of many tertiary amino substituted Z-aryl aryleneazoles that their fluorescent strength is superior towell known optical bleaching agents that have found commercial acceptance. These products have aflinity for both cellulosic and'non-cel'lulosic materials but are particularly useful for the latter. In the discussion which follows and in the examples, I will referto the 2 phenylbenzothia'zoles because these-compounds are the preferred embodiment of my invention.

ice

As indicated above, Z-phenylbenzothiazoles: which have 21 substituent, in which the R1 and R2 are defined asabove; are good optical bleaching agents for fibers but that they have a decided reddish blue shade of fluorescence. I have also noted that 2-phenyl'benzothiazoles which have a substituent, in which R1 and R2 have the same definition, are likewise good optical bleaching agents but that these compounds have a greenish blue shad-e of fluorescence. I have further found that. these classesyof compounds are good shading components, that is, the reddish blue class can be usedto cancel out greenish tinges of fluorescence and vice versa the greenish blue class can be used to cancel out reddish cast fluorescence. While it is. an especially good, blend if one of each of the above classes is present in the mixture, blends may also be made which contain more than two optical bleaching agents.

It is a further advantagevthat by using the compounds of my invention I obtain a flexibility of shade. Since the soap and detergent manufacturers have individual tastes in the shade of fluorescence desired, the chemical manufacturers find it diificult to supply all the desired shades. A great many compounds must be prepared to fill these needs; By using the compounds of my invention, it is necessarytomake only two products. By blending these in the proper proportions the specific taste of any customer can 'be readily supplied. The manufacturers can pick their own shades and the dyestulf manufacturer's need not maintain a large line of optical bleaching agents.

It-isanother advantage of the compounds of my invention that the dyes build up well on the fiber. This is especially true when each component of the blend is a member-of. one of the two be'nz-othiazole classes described above; Such; compounds when used in combination, build up evenly, maintaining the same shade and' having about the'same fastness properties.

While blendsof 4-dialkylamino-2-phenylbeniothiazoles with 6-dialkylamino-Z-phenylbenzothiazoles are a preferredv embodiment, either component can be used to shade other optical bleaching agents to get a desired shade. For example, there are many coumarin derivatives on the market as commercial optical bleaching agents for non cellulosic fibers. These can be mixed as desired with a member of either classof theZ-phenylben'zothiazole derivatives of my invention. A specific example. of this embodiment is the blending of a well-known optical bleaching agent, 4-methyl-7-diethylamino coumarin,

which has a reddish blue fluorescence, with one of the 6-dialkylamino-2-benzothiazoles to obtain a more neutral or even a slightly greenish shade of fluorescence. Other commercial optical bleaching agents have a greenish blue fluorescence and with these one can blend one of the 4"- dialkylarnino-2phenylbenzothiazole derivatives to. obtain a modified and'redder shade of fluorescence.

The'exact' shade of fluorescence of anys'pecific member of either class is not predictable. The shade varies. with the 'substituents on the molecule and the only prediction that can be made is that the positionof the dialkylarnino group determines whether the fluorescence is on the reddish or greenish side of pure blue. It is therefore not possible to predict accurately what the exact shade of the blend will be until tests have been'made. The exact composition which will givea' pure neutral fluorescence will be uniquefor any given combination and must be determined by experimentation. An example of such a composition is that in one of the preferred embodiments of my invention it takes 70 parts of 6-methyl-4'-dimethylamino-2-phenylbenzothiazole and 15 parts of G-dimethylamino-2-phenylbenzothiazole to produce a neutral blue fluorescence. Other substituents in the molecules produce different base shades and require different proportions.

I further find that the Z-phenylbenzothiazoles of my invention are also substantive on cellulosic fibers. This is most surprising in the absence of known substantive groups and in the absence of any solubilizing groups such as sulfonic acid groups.

I can therefore use them to blend with cellulosic optical bleaching agents such as diacylamino-stilbene-disulfonic acids, 1,3,5-triazinyl-diaminostilbene-disulfonic acid derivatives, tri-azinylaminoacylaminostilbene disulfonic acid derivatives and acylated benzidine sulfone disulfonic acids. It is possible, however, to sulfonate the compounds of my invention to make them even more soluble in Water and therefore even more readily usable in blending with cellulosic optical bleachmg agents.

It is a further feature of my invention that it is possible to use these compounds to whiten soaps and detergents. Because of the strength of fluorescence of these products as compared with the several commercial products much less optical bleaching agent may be required to produce the same effect. The compositions of matter of this embodiment of this invention may contain, for example, as the detergent component, sulfite cellulose Waste liquor or condensation products of naphthalene sulfonic acids which may be alkylated with formaldehyde, or other sponaceous cleaning agents which, as is known, are also good emulsifying agents. As examples of such sponaceous cleaning agents there can be named ordinary soaps, salts of sulfonated washing agents, for example, of sulfonated benzimidazoles substituted at the Z-carbon atom by higher alkyl radicals, monocarboxylic acid esters of 4-sulfophthalic acid having higher fatty alcohol residues, and also salts of sulfon-ated fatty alcohols or condensation products of higher fatty acids with aliphatic hydroxyor aminosulfonic acids. Such sulfonated washing agents are representatives of the group of the synthetic anion-active cleaning agents. The indicated sulfonated washing agents contain either the sulfonic acid group -SO3H or the sulfuric acid ester group OSOaH. They contain therefore radicals of sulfuric acid. In the compositions of matter of my invention it will be recognized that polyglycol ethers of a fatty alcohol may be present as an emulsifying agent.

Again the exact shade of fluorescence desired for a particular detergent may be obtained by blending 4' dialkylamino-Z-phenylbenzothiazoles with 6-dialkylamino-2- phenylbenzothiazoles, or by mixing either or both of the Z-phenylbenzothiazoles with certain other bleaching agents.

The material to be improved can be washed and bleached simultaneously with a composition of matter which contains a cleansing agent. An especially pronounced brightening effect is produced when undyed animal fibers, especially wool, are treated with mixtures containing such washing agents.

The compositions of matter used in the process of this invention may be also applied in the course of the manufacture fo the material to be improved. In this case the compound may be added, for example, to a paper mass or a viscose solution which is to be used for making films or filaments.

The compositions of matter of the invention may also be added, for example, to liquors used for imparting a crease resistant finish. They are also suitable for the after-treatment of discharge prints.

In a preferred embodiment of my invention I contemplate that solid blends of the two optical bleaching agents may be prepared and the mixture used as a unit in adding to soaps, dyebaths, and the like. Alternatively it is contemplated that different optical bleaching agents may be added separately in the proper proportions. For example, separate solutions may be prepared and the proper amounts of each added to the detergent to get the desired shade. Alternatively, such solutions of each optical bleaching agent or a solution of the blend may be added to the dyebath after the soap has been dissolved but before the fiber is immersed. Alternatively also, the

optical bleaching agents may be dissolved separately, or as a blend, in a non-aqueous solution and added directly to the fiber after the completion of the washing. The composition of matter which comprises the fibers dyed with the compounds of our invention therefore forms a separate and distinct embodiment of our invention.

The compounds of our invention can be applied to synthetic fibers, such as nylon, in for example aqueous lower alkanol solution, with or without the presence of detergents, to impart a desired sheen by virtue of the fluorescence of the dyes.

The 2-ary1 arylenethiazoles generally of a reddish blue shade of fluorescence to be used in my invention are those with an dialkylamino substituent in the aryl group, preferably in a position conjugated with the azole ring. For illustrative purposes, the general formula for the 2-phenylbenzothiazole derivative follows:

in which R1 and R2 represent aliphatic groups such as methyl, ethyl, propyl, isopropyl, butyl; or an alkenyl such as propenyl or butenyl; or an alkenyl such as propenyl or butenyl; or substituted alkyl such as chloralkyl, hydroxyalkyl etc; or cyclic radicals such as cyclohexyl. R1 and R2 may be the same or dilferent and may be joined together to form a ring. Other substituents may be present in either benzene ring, which substituents will modify the shade of the fluorescence. Among those compounds found to be effective are 4-dirnethylamino-6-methyl-2- phenylbenzothiazole, 4- dimethylamino- 2- phenylbenzothiazole, 4- diethylamino 6 methyl 2 phenylbenzothiazole, 4-diallylamino-6-methyl-2-phenylbenzothiazole, 4- dimethylamino-4- methyl-6- chloro-2- phenylbenzothiazole, 4'-dimethylamino-6-methoxy-2-phenylbenzothiazole, 4'-dimethylamino 6-ethoxy-2-phenylbenzothiazole, 4-dibutylamino-Z-phenylbenzothiazole, 4-di-isopropylamino- 6-methyl-2-phenylbenzothiazole, 4'-dirnethylamino-4,6,2'- trimethyl-Z-phenylbenzothiazole, 4-methyl-isoamylarnin0- 6-2'-dimethyl-2phenylbenzothiazole, 4'-bis (fi-hydroxyethyl)- and 4'-bis (fi-chlorethyl)-2-phenylbenzothiazole, 4'-dicyclohexylamino-2-phenylbenzothiazole, 2- piperidinyland 2-morpholinylphenyl benzothiazoles and the like. Other useful compounds are the 2-(4-dialkylaminophenyl) naphthothiazoles, the 2-(dialkylaminonaphthyl) benzoand napthothiazoles and the imidazoles and oxa- Zoles corresponding to the above compounds.

The preparation of these compounds proceeds by standard methods. One such method is the alkylation of the dehydrothio-para-toluidine or dehydrothio-xylidine. The use of the latter is one method of obtaining an alkyl substituent on the 2-phenyl ring. The alkylation can be carried out by the use of either alkyl halides or dialkyl sulfates. Alternatively, an ortho-aminothiophenol, with or without other substituents, can be condensed with a paradisubstituted-aminobenzaldehyde by the usual procedure. An alternative method is to acylate a bis(o-aminophenyl) disulfide with a paradisubstituted-aminobenzoyl chloride followed by the reduction of the disulfide to eifect ring closure. Then benzimidazoles and benzoxazoles are prepared by Well-known methods from the o-diamines and o-aminophenols respectively by condensation with the appropriate aldehyde.

The 6 disubstituted amino 2 phenylbenzothiazoles,

mam-tea whichare the preferred green shading components of my invention, have the general formula:

Most conveniently para-nitroso-N,N-disubstituted anilines (prepared by the action of nitrous acid on an N,N-disubstituted aniline) are condensed with sodium thiosulfate by a procedure described in the literature to produce a 2-amino-5-disubstituted amino benzene thiosulfur-ic acid. These compounds react directly wih aldehydes, as is known in the literature, to form 6 disubstituted amino 2 phenylbenzothiazoles directly. By the choice of the proper aldehydes various substituents may be introduced into the 2-phenyl portion of the molecule. By the'choice of the proper disubstituted anilines, substituents can be introduced into the other benzene ring of the molecule. One can start with any disubstituted aniline in which the substituent on the nitrogen is an aliphatic radical such as methyl, ethyl, propyl, butyl, and the like; or a lower a-lkenyl group such as propenyl or butenyl; or a substituted alkyl or cycloa-liphatic radicals as defined above. Among the compounds which may be prepared by this method are 6 dirnethylamino 2 phenylbenzothiazole, methyl 6 dirnethylamino 2 -'phenylbenzothiazole, 5 ethyl 6 dirnethylamino 2 phenylbenzothiazole, 4 methyl 6 dirnethylamino --2 phenylbenzothiazole, 6 diethylamino 2 phenylbenzothiazole, 6 dibutylamino 2 phenylbenzothiazole, 2'3 dimethoxy 6 dirnethylamino 2 phenylbenzothiazole, 2',4 dimethoxy- 6 dirnethylamino 2 phenylbenzothiazole, 4' methoxy- 6 dirnethylamino 2 phenylbenzothiazole, 3',4 dimethoxy 6 dirnethylamino 2 phenylbenzothiazole, 4' chloro 6 dirnethylamino 2 phenylbenzothiazole, 4 nitro 6 dirnethylamino 2 phenylbenzothiazole, and the like.

The fibers to which the compounds of my invention can be applied include wool, silk, super-polyamides, polyacrylonitriles, co-polymers of acrylonitriles, super poly esters, and the like. Also our products are substantive on cellulosic fibers such as cotton,rayon, cellulosic esters, and the like. Sulfonated derivatives are especially useful on protein fibers, such as wool or silk, and nylon.

My invention is further illustrated by the following examples in which parts are by weight unless otherwise specified.

Example 1 One hundred and twenty parts of dehydro thio-paratoluidine and 106 parts of anhydrous sodium carbonate are slurried in 400 parts of methyl alcohol. 142 parts of methyl iodide is added gradually. The mixture is then stirred at the reflux until the reactionis substantially complete. The mixture is then cooled and drowned in 4000 parts of water. The product is isolated by filtration and washing. The crude product is purified by dissolving in 1000 parts of five normal hydrochloric acid at 80 C. 200 parts of alcohol is added followed by a smaller amount of activated charcoal. The solution is clarified hot and the filtrate is cooled. The precipitatedamine hydrochloride is ba'sified andthe free amine is isolated by filtration and washing.

fBy the use of equivalent amounts stony; iodide and allyl bromide, respectively, the corresponding diethylamino and diallylamino derivatives are prepared following the same procedure.

' Example 2 v a CH:

i S CH3 One hundred and twenty-four parts of bis-ortho-aminophenyldisulfide and 164 parts of para-dimethylaminobenzaldehyde are added to 2000 parts of acetic acid. The mixture is stirred. at the boil until the reaction is substanr' tially complete. It is then cooled and drowned in 5000 parts of water. A yellowish tarry product precipitates and is separated'and dissolved in amixture of 1000 parts of ethyl alcohol and 500 parts of concentrated hydrochloric acid at the boil. The boiling solution is dec'olorized with charcoal and cooled. The precipitated product is isolated by filtration and reslurried in water. 'The slurry is made alkaline with ammonia and the free amine is isolated by filtration and Washing.

Exam? le 3 N CH3 Two hundred and twenty-one parts of the zinc salt of 2 amino 3 methyl 5 chlorothiophenol is added to 1500 parts of acetic acid. 150 parts of para-dimethylaminobenzaldehyde is added and the mixture is stirred at refluxuntil the reaction is substantially complete. It is then cooled and the precipitated product is purified by dissolving in a mixture of 3000 parts of ethyl alcohol and 500 parts of 5 normal hydrochloric acid at the boil. After a charcoal purification and clarification, the cooled filtrate is basified with ammonium hydroxide. The precipitated free amine is isolated by filtration and washing.

By using equivalent amounts of the zinc salts of 2- 'arnino-S-methoXy thiophenol or 2-amino-5-ethoxy thiophenol, the same procedure may be used to produce the corresponding 6 methoxy or 6 ethoxy 4' dimethylamino 2 phenylbenzothiazole.

Example 4 One hundred parts of dimethyl aniline is dissolved in 500 parts of concentrated hydrochloric acid. 300 parts of ice is added to the solution followed gradually by a solution of 70 parts of sodium nitrite in 200 parts of water. The mixture is kept below 0 C. during this addition and is stirred at 0 C. until the reaction is substantially complete. The product is isolated by filtration and dissolved in 800 parts of water. Thefree base is precipitated by adding ammonium hydroxide. The para-nitroso dimethy-laniline is isolated by filtering and is washed and dried. A solution of 300 parts of water, 29 parts of acetic acid, and 0.9 parts of sodium nitrite is heated to 68' C., and 15.1 parts of the para-nitro'so dirnethyl aniline is added. The mixture is stirred while a solution of 61.8 parts of sodium thiosulfate crystals in 300 parts of water is added. The solution is stirred at 70-72" C. until the reaction is substantially complete. A slurry of 11.7 parts of benzaldehyde, 100 parts of water, and 10 parts-of alcohol is then added. The mixture is stirred at C. until the reaction is substantially complete. parts of acetic acid is then added gradually and the mixture is cooled. The precipitated crystalline productis isolated byfiltration and dissolved in 300 parts of alcohol acidified with hydrochloric -acid The solution is clarified and diluted with 300 parts of water. The product is precipitated by basification with .ammonia. It is-isolated and washed neutral and dried.

It may be recrystallized from organic solvents to produce substantially complete. After eoolin'g, the solution is drowned on ice, filtered, and washed. The precipitate is dissolved in hot dilute alkali, clarified, cooled, and diluted with 3 volumes of saturated brine. The precipitate is do diethylamino-4-methylcoumarins z 7-din1ethylarnh1o-4-methylcoumarin.

zothiazole.

70 4dimethylami.no-2-phenylbenzothiazole.

81.5 -d.imethylamino-6-meth0xy-2-pheny1benzothiazole.

4 dimethy1amino-6-methyl-Z-phenyl-belia light yellow crystalline solid melting point 133135 C. 5 filtered and dried. The crude sodium salt is heated in By following the same procedure but substituting for a mixture of 600 parts of 50% ethanol and 30 parts of the benzaldehyde equivalent amounts of 2,3-dirriethoxy S-Norrnal hydrochloric acid for 2 hours at 90 C., cooled, benzaldehyde,2,4-dimethoxy benzaldehyde, 3,4-dimethoxy filtered, Washed with water, then dried. The resulting benzaldehyde, and 4-methoxy benzaldehyde, the correacid is dissolved in aqueous alcoholic alkali, charcoaled, spending dimethoxy or methoxy derivatives of the and salted to give the purified sodium salt in good yield. -fi-dimethylamirio-2-phenylbenzaldehyde are readily ob- By the use of this procedure, the products of Examples 2 mined.- to 6 can be similarly sulfonated to give water soluble Exam le 5 sodium salts. I V

NH p CH Example 8 v v A solution of 27.3 parts of dehydrothio-para-toluidine IQ- K sulfonic acid in 100 parts of Water and parts S-Normal sodium hydroxide is treated at room temperature with N I 41.2 parts of dimethyl sulfate. The mixture is basified A mixture f Parts of -p y dlamlne, with 30 parts of 5 N sodium hydroxide, heated at P s Of P-dimethylamino belflaldehyde and 5 Parts 9 20 85-90 C. for one-half hour and again basified with 20 zinc chloride is fused and stirred at 190200 un parts of S-Norrnal alkali. After the addition of a second the r ac i n is Substantialllf q p F' wohng the portion of 41.2 parts of dimethyl sulfate, it is basified with mixture solidifies. The solid is dlSSOlVCCi in hot water 75 parts of 5 1 Caustic and heated at g5 9 C,- containing hydrochloric P and with ch31" until the reaction is substantially complete. The solution: coal. After the clarification the filtrate 1S. cooled and a is cooled and treated with 110 parts of saturated brine to light colored p p PP Thls 1S lsolflted 3 give a voluminous precipitate which is filtered otf, dis-- filtration and reslurried in water. The slurry is made Solved i 500 parts ethanol, Chane-318d l ifi d and slightly alkaline h Sodlllm hYdYOXIdB and the f treated with 120 parts of concentrated hydrochloric acid. benzimidazole and isola ed y filtrfltlon and The slurry is heated to the boiling point to dissolve the The crude product may be recrystallized from a l t r precipitate, charcoaled, clarified, and diluted with 900 of 2parts of alcohol to 1 part of water. parts of water. The precipitate is filtered ofif, dissolved Example 6 in hot aqueous alkali, cooled, and salted to give a good N yield of the desired product. If desired, the material can be further purified by reconversion to the free acid fol- /CN\ 5 lowed by reformation of the sodium salt. OH: I Example 9 Two hundred and sixteen parts of o-arniiio phenol and Nylon cloth dyed the usual manner y adding all 296 parts of p dimethy1amin o benzaldfihyde is dissolved aqueous alcoholic solution of the optical bleaching agent in 2500 parts of alcohol and the mixture is refluxed until 40 to a detergem bath) Wlth the following c mpounds, with the reaction is substantially complete. The mixture is the rssults gwencooled and the precipitated Schitt-S base is isolated by filtration and washing. More of the product may be cqmpound Fluorescence isolated b eva oration of the mother liquor.

Twenty six garts of the Schiff base is dissolved in 500 4dimetby}ammo'6'mcthylaphenylbcnmthmzole $21535 A) parts of benzene at the boil. Forty-four parts of lead if gigmxfigf fiig ti i-lf g ggi gzggg i imgg g3?- tetra-acet ate is added and the mixture is boiled until the v y p L S a f'n i react on is substantially complete. The crystalline mass 'g "P which separates is filtered off, and the mother liquor is l3fi$i fififi fifi red evaporated. The residue is dissolved in aqueous hydro- 4tdimethylaminofi'methoXY"2'l?he}1Y1benzothiazole D05 U chloric acid and filtered. The filtrate is then basified i -iiifii31$Z3138 ifiififiiifiifiiiihtiiZ3:"323 B? A with ammonium hydroxide and the free benzoxazole e'dimethylaminoz'phenylbgnmthiazole greenish P which precipitates is isolated by filtration, Washing, and 4-methoxy-fi-dimethylanilno-2-phenylbenzothiazo1e. sllig hft i y frei ltii drying. The crude product is iecry stallized from 60 parts 2,3,:dimcthoxyfimmethylammo 2 pheny1benm t B of alcohol plus 25 parts of water with a charcoal decolorthiaz ie. ization. The recrystallized product is isolated by filtrat ggfigfi tion and washed and dried. A further crop of purified C yy -p e y 0- oproduct may be isolated by dilution of the mother liquor thiazole with water, Cellulose acetate or Wool cloth, dyed in the same manner,

Example 7 gives similar results.

Five parts of the product of Example 1 is dissolved in Example 10 150 parts of 7% oleum. The solution is stirred and heated Nylon cloth is dyed by the standard procedure with the to 120 C. and held at -120 C. until the reaction is following blends:

Parts Reddlsh Blue Component Parts Greenlsh Blue Component Fluorescent Shade 79 et gfigiigiammo-fi-methyl-2-phenylben- 21 6-dimethylamino-2-phenylbenzothiazole approximately neutral. g greddish blue.

greenish blue. slightly greenish. .do greenish.

6 -dlmethylamino- 4 methoxy -2 -pheny1- benzothiazole. fi-dimethylamino-Z-phenylbenzothiazole. slightly greenish. do fairly neutral.

approximately neutral.

Example 11 Cotton cloth is dyed by the standard procedure with the following blends:

phenylbenzothiazole and 6-dimethylamino-Z-phenylbenzothiazole.

5. The composition according to claim 4 which comprises a mixture of 79% of 4-dimethylamino-6- Parts Reddish Blue Component Parts Greenish Blue Component Fluorescent Shade 25 4 dimethylamino 6 methyl 2 phenyl- 75 3,7-bis(2 4- dimethoxybenzoylarnino) diredder than the sulbenzothiazole. henzot 'ophene 5,5 dioxide 2,8- ionic acid alone.

disulfonic acid, sodium salt.

80 4,4 bis(2,4 dimethoxybenzoylarniuo) 20 6 dimethylamino 2 phenylbenzogreener than the sulstilbene 2,2 disulfonic acid, sodium thiazole. fonic acid alone. salt.

85 4,4 -bis(2,4-diani1ino 1,3,5 -triazinyl-6- 6 dimethylamino 4 methoxy 2 Do.

amino) stilbene 2,2 disulfonic acid, phenylbenzothiazole. sodium salt.

75 4,4 bis(2 ethoxybenzoylamino) stilbene 25 6 dimethylamino 2 phenylbenzothiaslightly greenish blue.

2,2-disulfonic acid, sodium salt. 2010.

25 Sulfonated 4 -dimethylarnin0 fi-rnothyl- 75 3,7 bis(2,4 dimethoxybenzoylamino) redder than the sul- Q-pheuylbenzothiazole. dlbenzothiophcne 5,5 dioxide 2,8 ionic acid alone.

disulfonie acid, sodium salt.

80 4,4 bis(2,4 dimethoxybenzoylamino) Sulfonatcd 6-dimethy1amin0-2-phenylgreener than the sulsti1bene-2,2-disulf0nic acid, sodium salt. benzothiazole. ionic acid alone.

85 4,4 bis(2,4 diam'lino 1,3,5 triazinyl -16 15 Sulionated 6 dimethylammo 4 -meth- Do.

almino)alstilbene-2,2-disulionic acid, 50- oxy-2-phenylbenz0thiazole.

ium s t.

75 4,4 bis(2 ethoxybenzoylamino)stilbene- SuIfonatedG-dimethylamino-2-phenylslightly greenish blue.

2,2-disu1fonie acid, sodium salt. benzothiazole.

I claim: methyl-Z-phenylbenzothrazole and 21% of 6-d1methyl- 1. Optical bleaching agent compositions comprising a mixture of 62-93.5% of a 4'-tertiary amino substituted 2-phenylbenzothiazole and 65-38% of a 6-tertiary amino substituted 2-phenylbenzothiazole in which the substituents on the amino nitrogen are aliphatic groups, each of said groups being of less than 7 carbon atoms, the said aliphatic groups being free of acidic and basic substituents.

2. The compositions according to claim 1 in which the 4-tertiary amino substituted 2-phenylbenzothiazole is a 4'-dirnethylamino-2-phenylbenzothiazole.

3. The compositions according to claim 1 in which the G-tertiary amino substituted 2-phenylbenzothiazole is a 6-dimethylamino-Z-phenylbenzothiazole.

4. Optical bleaching agent compositions according to claim 1 comprising a mixture of 4'-dimethylamino-2- 25 amino-Z-phenylbenzothiazole.

References Cited in the file of this patent UNITED STATES PATENTS 2,037,448 Alleman Apr. 14, 1936 2,347,644 Sell May 2, 1944 2,550,321 Ackermann Apr. 24, 1951 2,600,004 Krahler June 10, 1952 FOREIGN PATENTS 999,047 France Sept. 26, 1951 OTHER REFERENCES Hunter: Chem. Abstracts, vol. 18, page 984(1924). Bogert et al.: Chem. Abstracts, vol. 26, page 1281 (1932). Ast et al.: Chem. Abstracts, vol. 30, page 2193 (1936). 

1. OPTICAL BLEACHING AGENT COMPOSITIONS COMPRISING A MIXTURE OF 62-93.5% OF A 4''-TERTIARY AMINO SUBSTITUTED 2-PHENYLBENOTHIAZOLE AND 6.5-38% OF A TERTIARY AMINO SUBSTITUTED 2-PHENYLBENOZTHIAZOLE IN WHICH THE SUBSTITUENTS ON THE AMINO NITROGEN ARE ALIPHATIC GROUPS, EACH OF SAID GROUPS BEING OF LESS THAN 7 CARBON ATOMS, THE SAID ALIPHATIC GROUPS BEING FREE OF ACIDIC AND BASIC SUBSTITUENTS. 